Terminal for electrical measuring instruments



Sept. 14 1926.

, w. H. woop TERMINAL' FOR ELEpTRIcAL mmunme ms'rnumsms Filed Jpne 25. 1920 AT ORNEY INVENTOR VW/I'am h. L. Wand WITNESSES: QQQaMaM creased in order to enable it tov withstand Patented gept. 14, 1926. i

I siren; srarss T N 5552i WILLIAM VH7; L. woon, or MAivorrnsrnn, ENGLANE' ASSEGNOR TO wnsrinciaousn ELECTRIC. a MANUFACTURING 00., A oonronnrrron or r'nmvsynvarrm.

TERMINAL pron ELECTRICAL V MEASURING msrnmunnrs.

Application filed June as, iaaaseria No. 391,749, and in England June 27,1919;

- I My invention relates to the insulation of the leads passing through the cases of electrical'measuring instruments and thelike and is'especially applicable to those instruments which are intended to be attached to a switchboard or panel where it is necessary to make provisionfor passing leads or rods thr'oughthe panel and through the back of the instrument case into the interior thereof in order to make the necessary electrical connections. a

The object of my invention-is to provide an improved terminal forelectrical measuring-instruments.

It has hitherto been the practice to? pro vide for insulating the leads or rods, where they-extend through the case of an instrument, by means of a bushing of hard rubber or other suitable insulating material that is provided with a flange and that maybe secured by screws extending through the flange into the instrument case. It has also been a common practice to provide such bushing withan internal-sleeve of brass 25- having a square flange-embedded in the bushmg,the 111t6I10IOf which sleeveis so screw-threadedthat a terminal post .may

be screwed thereinto from the inside of the instrument and a rod,,-which extends throughthe panel of the switchboard, maybe screwed'into the other end of the sleeve, thus enabling a connection to: be, made.

through the switchboard to the instrument terminals. It has been found, however, that considerable strain is placed upon thein 'sulating bushing whenthe rods. are screwed up, thus tendingto burst; the insulation .or

is secured to the instrumentcase, and the SlZG'OftllG bushing has, therefore, been inthe strain. Breakage-isalsoliable to occur if: any pressure is accidentally appliedflto capof metal that may be secured to the instrument case by screws that are adapted regular perimeter, it is preventedfrom r0 tatlng therein. totear it: away from the screwsiby which 1t;

to extendthrough the cap orthrough lugs attached thereto.

In order that the nature of the; invention may be clearly understood,it will now be described with reference to the accompany ing drawing in which 1 F igurel is a front elevational view ofa terminal'embodymg my mventionyandlFHg.

2 is a side view, partially in" elevation and partiallyin section, of the terminal shown in Fig.1..

Referring to the drawings, the terminah I comprises a bushing 2 of suitable insulating material that does not require greatgmechanical strength but must be able to resistfa certain amountof compression. The bushing 2 is provided with a flange-,3, the perimeter of whichisof substantially polygonal, V

or irregular shape, that isen'closed, except,

on the side that isto be applied to. the case 4 of the instrument, by a closely fitting ca 5 of brass or other suitable sheet metal. The. bushing '2 projects through the plane face panel 10, may be threaded into the oppo-- site endof the sleeve 6. Since-flange 7 projects laterally intothe bushing 2 in which it is embedded, it is prevented from being pulled. or pushed out ofv the bushing an since it is provided with a polygonalor ir-" The terminal maybe secured to-thefcase 4: ofthe. instrument by means of a plurality of screws 111.;that' extend through openings plane face of the cap 5 and through openings in the bushing 2 that are prefer ably slightly'larger than theopeningsin the cap or hy-means of screws that extend throughylugs that may be provided proin the jecting= from the sides ofthecap; V The terminal may preferably be, disposed withinthe' instrument case since, if it were attachedon the outside thereof, it could be removed and the usual sealing of the instru ment cover rendered useless.

It will beseen that, with the improved construction, any tendency to breakthe, in-

n A- A) a spouse to said turning forces to sulating bushing by turning the metal sleeve or the rods screwed thereinto Wlll be prevented because the breaking strain Will be transmitted by the irregular perimeter of the flange 7 to the sides of the enclosing cap and, from the cap to the case 4L- through the screws 11. The insulating material will merely be placed in compression between the flange 7 and the sides of the cap 2.

\Vhile 1 have shown a preferred form of terminal embodying my invention, I do not limit it to the specific structure shown as various modifications may be made therein Within thespirit and scope of the invention as set forth in the appended claims.

I claim as my invention:

1. In a terminal, the combination with a base member, of an insulating member hav ing a portion outside said base member, a conductor in saidinsulating member subject to turning forces, and a reinforcing member for said outside portion secured to said base member, said conductor and reinforcing member having portions cowoperating in response to said turning f ces .to chaos said insulating member in co iression, and to Widely distribute said forces in the insu'lat ing member, between them.

2. In a terminal, the combination with a base member, of an insulating member having a portion outside said base member, a conductor in said insulating member subject to turning forces, and a reinforcing jacket surrounding said outside portion and secured to said base member, said conductor and jacket having portions co-operating in response to said tin-hing forces to place said insulating member in compression, and to Widely distribute said forces in the insulating member, between them.

In a terminal, the combination with a base member, of an insulating member'having a portion outside said base member, a conductor in said insulating member subject to turning forces, a relatively thin sheetmetal reinforcing jacket surrounding said outside portion, an'dmeans cooperating with the jacket for securing the insulating member to the base member, said conductor and jacket having portions co-operating in replace said insulating member in'compression, and to Widely distribute said forces in the insulat ing member, between them. i'

4. In a terminal, the combination With a base member, of an insulating member having a portion outside said base member, a conductor in said insulating member sub ect to turning forces, a relatively thin sheetmaterial reinforcing jacket of substantially cup-shape surrounding said outside portion, and means co-operating with the jacket free of the insulating member for securing the latter to the base member, said conductor and jacket having portions co-operating in response to said turning forces to place said insulating member in compression, and to widely distribute said forces in the insulating member, between them.

0. In a terminal, the combination with a base member, of an insulating member hava portion outside said base member, a conductor in said insulating member subject to tanning forces, a relatively thin sheetmetal .reiirforcing jacket of substantially cup-shape surrounding said outside portion, and screws extending :through the outer Wall of the jacket and through the insulating member "free of the ilatter for securing the same to :the base member, said conductor and jacket having portions co-operating in response to said turning forces to place said insulating member in' Compression and to Widely distribute said forces in the insulat ing member between them.

6. In a terminal, the combination with a base member having {an opening therethrough, of an insulating bushing having a portion in said opening and a portion outside the same, a conductor in said bushing subject to turning forces and a reinforcingjacket for said outside portion-of the bush ingsecured to said .base;p late,said conductor and jacket having portions (Jo-operating in response to Said zturni'ng forces to place said bushing in compression, and :to widely idistribute said forces in thebushing, between them.

7. In a terminal, the coni'bination'with a base member, of an insulating member having, a polygonal portion outside said'base member, a conductor in said insulating member :having a polygonal portionsubject to turning forces in said outside portion thereof,and a reinforcing jacket enclosing, and conforming to, said polygonal outside portion of theinsulating member and se cured to said base member, said polygonal portions co-operat-ing to prevent damage to the insulating member by placing portions of the latter in relatively broad flat compression between them.

In testimony whereof, I have hereunto subscribed my name this first day of June,

V WILLIAM H. L. WOOD. 

